U.S. Pat. Nos. 4792133 and 4852870 disclose substitute ground surface materials comprising sand and other particulate material which is coated with a binder formed from an oil having the consistency of a soft grease at normal temperatures with a polymer dissolved or dispersed therein. The oil is typically a petroleum oil fraction having a viscosity of about 10000 centipoise at 20.degree. C. and typical polymers are ethyl vinyl acetate, polystyrene, nylon, polypropylene, poly vinyl chloride and styrene-butadiene-styrene copolymers included in amounts of about 1 part polymer to 9 parts oil. The material typically comprises dry sand and binder in a ratio of 100:6.5.
These materials suffer from the problem that their physical properties are mainly dictated by the properties of the oil in the binder and soft greases typically change to free flowing oils at about 85.degree. F. This means that when high climatic temperatures are encountered, the properties of the material can change dramatically.
It is an object of the present invention to provide a ground surface material which is better able to retain its desired properties at high and low climatic temperatures.